Women with an optimistic outlook on life may live longer, a new study finds.
Optimistic women in the study were less likely to die from five major causes of death over an eight-year period than women who were less optimistic, according to the study.
And although optimism has been linked in earlier studies to healthy behaviors such as eating a healthy diet and getting more exercise, the researchers noted that these behaviors only partially explained the link to a longer life. [7 Things That Will Make You Happy]
In other words, it's possible that optimism directly impacts our biological systems, Eric Kim, a research fellow in social behavioral sciences at Harvard University's T.H. Chan School of Public Health and a co-lead author of the study, said in a statement.
In the study, which was published online today (Dec. 7) in the American Journal of Epidemiology, the researchers looked at data on women who were enrolled in the ongoing Nurses' Health Study, which began in 1976. Every two years, the women in the study fill out questionnaires about their health.
The current analysis included data from 70,000 women who had responded to a 2004 questionnaire that assessed their levels of optimism. The average age of the women in 2004 was 70 , according to the study.
The researchers also obtained information from state records and the National Death Index, along with reports from family members, about the women within this group who had died between 2004 and 2012. Doctors reviewed death certificates to determine the cause of death, and for the five causes, the researchers looked at whether the women's risk of dying from that cause was linked with their levels of optimism.
The researchers found that the most optimistic women had an overall risk of dying during the study period from any of the five causes of death analyzed that was nearly 30 percent lower than that risk among the least optimistic women.
Optimism appeared to have the greatest effect on the risk of dying from an infection: The most optimistic women were 52 percent less likely to die from an infection, compared to the least optimistic women. In addition, the most optimistic women were 39 percent less likely to die from stroke, 38 percent less likely to die from heart disease and 38 percent less likely to die from a respiratory disease than the least optimistic women. [The Odds of Dying]
A smaller effect was observed for cancer deaths, with a 16 percent reduction in risk of dying for the most optimistic women compared to the least optimistic women.
The researchers noted that this is one of the first studies that identified a link between optimism and the risk of dying from either an infection or a respiratory disease. One plausible hypothesis for optimism's effect on the risk of dying from an infection is that optimism has been associated with better immune system functioning in previous studies. And for respiratory disease, an earlier study found a link between optimism levels and pulmonary function.
Indeed, previous research has suggested that optimism is associated with a number of aspects of a person's health, according to the study. For example, optimists are more likely to have healthier cholesterol levels and lower levels of inflammation.
A limitation of the study is the possibility that the findings reflect "reverse causation," or in other words, that women's underlying health conditions could influence how optimistic they are, the researchers wrote. In addition, the links between optimism and infection and respiratory disease "should be interpreted cautiously because of the novelty of the findings," they wrote.
Originally published on Live Science.